Comment 2 for bug 1840677

On a 19.10 system without those packages:

root@e:~# apt-cache policy gir1.2-gtksource-4 libgtksourceview-4-0 libgtksourceview-4-common
gir1.2-gtksource-4:
  Installed: (none)
  Candidate: 4.3.1-2
  Version table:
     4.3.1-2 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages
libgtksourceview-4-0:
  Installed: (none)
  Candidate: 4.3.1-2
  Version table:
     4.3.1-2 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages
libgtksourceview-4-common:
  Installed: (none)
  Candidate: 4.3.1-2
  Version table:
     4.3.1-2 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages

# dpkg -l '*gtksource*'
dpkg-query: no packages found matching *gtksource*

I couldn't break it, but I ran into different issues ... ?!